240-222 CPT: Strings/10 1

240-222 Computer Programming Techniques240-222 Computer Programming TechniquesSemester 1, 1998Semester 1, 1998

Objectives of these slides:– to discuss string and file functions for the

project

10-1. StringsChapter 8-1

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Overview:Overview:

1. strstr

2. sscanf

3. atoi

4. fgets

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1. strstr1. strstr

char *strstr(const char *s1, const char *s2)

Locates the first occurrence in string s1 of string s2.

If the string is found, a pointer to the string in s1 is returned. Otherwise a NULL pointer is returned.

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Use:Use:

char *string1 = “abcdefabcdef”;

char *string2 = “def”;

printf(“%s%s\n%s%s\n\n%s\n%s%s\n”,

“string1 =“, string1, “string2 =“, string2, “The remainder of string1 beginning with the”, “first occurrence of string2 is:, strstr(string1, string2));

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Output:Output:

string1 = abcdefabcdef

string2 = def

The remainder of string1 beginning with the

first occurrence of string2 is: defabcdef

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2. sscanf2. sscanf

int sscanf(char *s, const char *format, …)

Equivalent to scanf except the input is read from the array s instead of reading from the keyboard.

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Use:Use:

char s[] = “31298 87.375”;

int x;

float y;

sscanf(s, “%d%f”, &x, &y);

printf(“%s\n%s6d\n%s%8.3f\n”,

“The values stored in character array s are:”,

“Interger:”, x, “Float:”, y);

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Output:Output:

The values stored in character array s are:

Integer: 31298

Float: 87.375

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3. atoi3. atoi

int atoi(const char *nptr)

Converts the string nptr to int.

long atol(const char *nptr)

Converts the string nptr to long int.

continued

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Use:Use:

int i;

i = atoi(”2593");

printf(”%s%d\n%s%d\n”,

“The string \”2593\” converted to int is “, i,

“The converted value minus 593 is “, i - 593);

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Output:Output:

The string “2593” converted to int is 2593

The converted value minus 593 is 2000

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4. Other functions4. Other functions

fgets Reads a line from a specific file.

rewind Causes the program to reposition the file

position pointer for the specified file to the beginning of the file